A saddle-ridden type vehicle such as a motorcycle may include an engine having a supercharger so as to improve a fuel consumption and an output. The engine having the supercharger has a cooling device for cooling an oil cooler and the supercharger.
For example, the cooling device of the engine having the supercharger disclosed in Patent Document 1 has a cooling water passage (for discharge) configured to supply cooling water, which is discharged from the engine, to a radiator and a cooling water passage (for supply) configured to supply the cooling water cooled at the radiator to the engine. The oil cooler and the supercharger are connected to the cooling water passage (for discharge) via two cooling water supply passages disposed in parallel. Two cooling water discharge passages extending from the oil cooler and the supercharger converge on the way, which is connected to the cooling water passage (for supply). A water pump for pumping the cooling water to the engine is interposed on the cooling water passage (for supply).
Most of the cooling water discharged from the engine is cooled while passing through the radiator, and is again supplied to the engine through the cooling water passage (for supply). A part of the cooling water discharged from the engine passes through the two cooling water supply passages and cools the oil cooler and the supercharger. The cooling water having cooled the oil cooler and the supercharger passes through the two cooling water discharge passages and converges on the cooling water passing through the cooling water passage (for supply).
Patent Document 1: Japanese Patent No. 2688828B
In the above technology, the oil cooler and the supercharger are cooled using the cooling water having cooled the engine. However, in some cases, it is not possible to sufficiently cool the oil cooler and the supercharger by the cooling water of which temperature has increased after cooling the engine. Also, the high-temperature cooling water having cooled the supercharger and the like is mixed with the low-temperature cooling water cooled at the radiator in the cooling water passage (for supply). In this case, the temperature of the cooling water that is to be supplied to the engine becomes unstable.